The density and speed of integrated circuit elements have steadily and exponentially increased for several decades, allowing for ever faster processing speeds, greater data handling capabilities, increasing storage capacity, and smaller physical dimensions of mobile electronic devices, such as smart phones, tablets, media players, global positioning system (GPS) and personal digital assistants (PDAs). With the ever increased amount of information available on computer networks as well as mobile devices' processing power and their abilities to provide access to data, users have become accustomed to using mobile devices at any desired location for prolonged times.
Wireless charging is gaining attentions from the mobile device manufacturing industries, such as inductively charging and solar charging. In contrast to traditional wired chargers, a wireless charger does not require metal coupling mechanisms (e.g., electrodes on the sockets) for transferring power from the charger to a mobile device being charged. Thus, wireless charging approaches potentially enable the development of water-proof mobile devices.
Mobile devices integrated with solar cells can be charged when the solar cells are exposed to sunlight or other ambient light. Solar charging offers a wireless, clean, cost-effective and convenient charging approach. However, solar charging efficacy is largely contingent on the intensity of and the exposure time to the ambient light, which sometimes cannot meet the users' requirements for reliable and consistent charging, e.g., in a raining or cloudy day or in the night. Currently, mobile devices with solar cells have to preserve the capabilities of wired charging for rapid charging, especially when the ambient light intensity is insufficient for solar charging. Wired charging dictates user accessibility to the electrode interfaces for connection to wall power, which may complicate efforts to make the device housing water-proof.